March 2 – Data sent from the Galileo space probe indicates that Jupiter's moon Europa has a liquid ocean under a thick crust of ice.
March 5 – NASA announces that the Clementine probe orbiting the Moon has found enough water in polar craters to support a human colony and rocket-fuelling station.
October 29 – Space Shuttle Discovery blasts-off with 77-year-old John Glenn on board, making him the oldest person to go into space up to that time. He became the first American to orbit Earth on February 20, 1962.
September 11 – First portion of upper body (an upper arm bone, followed later by the skull) of "Little Foot" (Stw 573), a nearly complete young female Australopithecus fossil skeleton capable of walking upright is found in the cave system of Sterkfontein, South Africa eventually dated at around 3.67 million years BP.[6]
May 28 – Nuclear testing: The Chagai-I: In response to India, Pakistan conducts five underground and simultaneous nuclear weapon-testing experiments in the Chagai Hills, thus becoming the first nuclear weapon state in the Muslim world and the seventh in the world.
May 30 – Nuclear testing: The Chagai-II: As part of a tit-for-tat policy, a final plutonium implosion test is carried out in the Kharan Desert.
June 5 – Experimental proof is obtained that neutrinos have mass.[8]
Physiology and medicine
January 14 – Researchers in Dallas, Texas, present findings about an enzyme that slows aging and cell death (apoptosis).